Substrate processing systems that subject semiconductor substrates (e.g., wafers) to various cleaning processes in semiconductor device fabrication often include processing liquid recovery systems configured for recovering and reusing the normally expensive processing liquids for processing additional substrates. The processing liquid recovery systems usually include one or more filters for removing film fragments and other impurities from the processing liquids prior to processing additional substrates.
For example, when a patterned resist film on a substrate is exposed to a processing liquid containing an organic solvent in order to dissolve and remove the patterned resist film from the substrate, the patterned resist film may only partially dissolve in the processing liquid but form film fragments that detach from the substrate and become suspended in the processing liquid. Next, the processing liquid and the film fragments are flowed through the processing liquid recovery system where the film fragments and other impurities are removed from the processing liquid.
However, due to the large number of wafers normally cleaned in conventional substrate processing systems and the often large amount of film fragments that become suspended in the processing liquids, the one or more filters used for filtering the processing liquid in the processing liquid recovery system may quickly become clogged, thereby hindering flow of the processing liquid through the one or more filters. This requires frequent cleaning or replacing of the one or more filters, which in turn interrupts the wafer processing, results in decreased wafer throughput, and increases the cost of operating the substrate processing system.